Effects of Six Single Species of Coccidia on Egg Production and Culling Rate of Susceptible Layers

IT IS generally accepted that coccidiosis in susceptible layers causes marked reduction in egg yield. However, there have been few controlled trials demonstrating either the duration of reduced production or the period required for full recovery. Limited observations on effects of different species of coccidia on egg production have been made. Temporary cessation in egg production in hens inoculated with E. acervulina, E. maxima and E. tenella has been reported by Johnson (1932) who also noted a slight decrease in egg production in birds inoculated with E. mitis and E. praecox. Johnson was also the first to report (1933) that fowls unexposed to immunizing coccidia during the rearing period might be affected with disastrous death losses in the laying house. Edgar (1958a) reported that hens kept coccidiosis-free and subsequently inoculated with 1,000,000 oocysts of E. tenella at 6, 12 and 18 months suffered weight loss, cessation of egg production and…